With the weather turning cool and the fall harvest beginning to come in, you may think the time for sowing seeds is past. And for most seeds, you would be right. But there is one class of seeds you could usefully plant in the next week or so if you’re here in Zone 7, and that’s winter cover crops.
Soil is a living thing–a living community, really. And it stays healthy only when it’s in constant partnership with plants. This includes during the winter months, when plants continue to protect soil nutrients from leaching, provide homes for beneficial insects, feed beneficial soil organisms, and produce organic matter that, come spring, can be reincorporated into the soil, thus increasing the soil’s humus content, fertility, and water retention. A bare winter garden is a garden that’s losing fertility, and to avoid that prospect, it’s useful to sow winter cover crops.
Cover cropping is not an easy technique to learn, however. The cover crops that work are very specific to local conditions: how cold your winters are, how wet your springs, how easily your soil drains, and the equipment you have on hand for cutting and turning under the crops in the spring. Many cover crops you read about are appropriate for farmers with large machinery but not for the home gardener. That’s why it’s important to get local advice and to start small, so you can get a feel for how the crops behave and interact with the timing of spring plantings in your area.
I admit that I’ve been somewhat intimidated by the literature on cover cropping, because of the enormous number of suggestions out there that lack any detailed information about how tall and strong I can expect the crop to grow here in Virginia, when I should expect to be able to turn it under, etc. This year, however, I’m finally going to try my first cover-cropping experiment, using guidelines given by Southern Exposure Seed Exchange, located just a few counties west of me. For areas that will not need to be planted first thing in the spring (that is, not areas where you want to plant peas or other early crops), Southern Exposure recommends using as a cover crop a mixture of winter rye and hairy vetch, with 4 lbs. of rye to each 1 lb. of hairy vetch, sown between Aug. 1 and Nov. 1. This combination can be tilled under in spring or, after the hairy vetch is in full bloom, mown to produce a weed-suppressing living mulch, into which tomato plants can be directly transplanted.
That is what I’m going to attempt this year, and so just today I sowed 100 sq. ft. as a test plot. First I loosened the soil with a hoe. Then I broadcast 6.5 oz. of winter rye followed by 1.5 oz. of hairy vetch and gently worked the top 1/4″ or so of soil with the hoe, to help bury most of the seeds. I’m not going to sow any more than this until I see how easy it is to handle in the spring.
If you have any tips for winter cover cropping here in Virginia, I’d love to hear them. Also feel free to tell me about your adventures cover cropping elsewhere. I’m always interested in learning how things are done in other regions, and your advice may be of immediate practical use to some other readers!